4-Phenylpiperidine compounds

ABSTRACT

The invention relates to new 3-substituted 1-alkyl-4phenylpiperidines, being useful as antidepressant and antiParkinson agents, and to their production.

United States Patent 1 Christensen et al.

[ Oct. 14, 1975 [54] 4-PHENYLPIPERIDINE COMPOUNDS [75] Inventors: Jorgen Anders Christensen, Virum; Richard Felt Squires, Gl. Olstykke, both of Denmark [73] Assignee: A/S Ferrosan, Denmark [22] Filed: Jan. 21, 1974 [21] Appl. No.: 435,006

[30] Foreign Application Priority Data Jan. 30, 1973 United Kingdom 4496/73 [52] US. Cl. 260/293.58; 260/293.73; 260/293.8l; 260/293.83; 260/293.84;

[Sl] Int. Cl. C07D 211/22 4/1965 Clarke 260/294.7

Primary Examiner-G. Thomas Todd Attorney, Agent, or Firm-Wenderoth, Lind & Ponack ABSTRACT The invention relates to new 3-substituted l-alkyl-4- phenylpiperidines, being useful as antidepressant and anti-Parkinson agents, and to their production.

8 Claims, No Drawings 4-PHENYLPIPERIDINE COMPOUNDS The present invention relates to novel 4- phenylpiperidine compounds and their salts with pharmaceutically acceptable acids, that are useful as pharmacological agents and to means for their production.

ing the general formula:

CH,OR

wherein R represents an alkyl or alkynyl group having 1-4 carbon atoms, or a phenyl group optionally substituted by lower alkyl, alkylthio, alkoxy, halogen, nitro, acylamino, methylsulfonyl, methylenedioxy, or tetrahydronaphthyl, R represents alkyl or alkynyl, and X represents hydrogen, alkyl having 14 carbon atoms, alkoxy, trifluoroalkyl, hydroxy, halogen, methylthio, or aralkyloxy. v

Where not otherwise specified, the alkyl, alkynyl, and acyl groups are preferably having 1-4 carbon atoms. The aromatic part of the aralkoxy group is preferably unsubstituted phenyl.

Examples of alkyl groups are methyl, ethyl, propyl, isopropyl, n-butyl, and tert.butyl, also as parts of the alkoxy and alkylthio groups.

Examples of alkynyl groups are -ethynyl,-propynyl,

antidepressants and anti-Parkinson agents. The compounds, wherein R is phenyl, f4-methoxyphenyl, and

1,3-benzdioxylyl, have provedparticularly valuable in thesaid respects.

The compounds of formula I are prepared from the CH,SO,CI

corresponding carbinols which can be prepared by reducing a compound of the formula ll COOCH where R and X are as hereinbefore defined, preferably with a complex metal hydride reducing agent, especially lithium aluminium hydride.

Compounds having the formula II may be prepared according to J. T. Plati, A. K. Ingberman and W. Wenner (J.Org.Chem. 1957: 22, 201) who prepare the compound in which X is hydrogen and R is methyl by treating arecoline (methyl-l,2,5,64etrahydro-3-pyridine-carboxylate) with phenyl magnesium bromide.

In the same manner, other compounds used as starting material for the desired piperidine carbinols are prepared using the appropriate arecoline homologue and X-phenyl magnesium bromide. The reaction gives the twoisomers, the cis form (a) and the trans form ([3) (carbon atoms 3 and 4 in the piperidine ring). Both forms can again be resolved into a and a form.

The compounds of the invention may be prepared from the piperidine carbinols using different processes.

- Method A Method c Two hydroxy compounds are condensed using dicyclohexylcarbodiimide as a condensing agent:

CHzOH In this method the a-carbinols give a-ethers, and the B-carbinols give a mixture of aand B-ethers.

According to another method the compounds of the invention are prepared from compounds of formula I, wherein R and X are as defined previously, and R in this case is hydrogen or an acyl group.

If R is hydrogen, the compound is alkylated, and if R is an acyl group, the group is reduced to give the corresponding alkyl group, or the acyl group is removed by hydrolyzing to leave the NH group which is then alkylated.

Usually one of the optical active forms of the new compounds is therapeutically more active than the other. To isolate this form the resolution may be accomplished as described in Example 3, or the resolution may be accomplished at an earlier stage, before the carbinol group of the piperidine is converted to an ether group.

The following Examples are illustrative of the comi pounds of the invention and their preparation without being limiting.

EXAMPLE 1 3-( (4-Meth oxyphenoxy)-methyl l -methyl-4- phenylpiperidine hydrochloride "tassium carbonate. Removal 'of the. solvent in vacuo (maximum 25C) gave the methanesulfonic acid ester as an oil. Yield I20 g.

b. To a solution of sodium.( 17.5 g) in dry-methanol (210 ml) was added a solution of 4-methoxyphenol (87.5 g) in methanol (140 ml) and a solution of the methanesulfonic ester of 3-hydroxymethyl-l-methyl-4- phenylpiperidine (105 g) in methanol (200 ml). The mixture was stirred and refluxed for 16 hours. After removal of the solvent in vacuo, the evaporation residue was poured into a mixture of ice (150 g), water (150 ml), and ether (200 ml). The ether layer was separated, and the aqueous layer was extracted with ether.'The combinedether solutions were washed with water and agitated with 2N hydrochloric acid (200 ml) to give a crystalline precipitate which was dried. Yield 56.8 g. M.p. 236-239C.

Recrystallization from 97% ethanol gave 52.3 g of 3- ((4methoxyphenoxy )-methyl l -methyl-4- phenylpiperidine hydrochloride, .m.p. 237239C.

EXAMPLE 2 3 -Methoxymethyl-l -methyl-4-phenylpiperidine To a solution of sodium (15.2 g) in methanol (270 ml) was added a solution of the methanesulfonic acid ester of 3-hydroxymethyl'- l -methyl-4-phenylpiperidine (121 g) in methanol (270 ml). The mixture was stirred and refluxed for 16 hours. The solvent was removed in vacuo, and the evaporation residue was poured into ice-water. The mixture was extracted with ether, the ether extract was dried over potassium carbonate, and the ether was evaporated. The evaporaton residue was distilled in vacuo to give 66 g of 3-methoxymethyl-lmethyl-4-phenylpiperidine. B.p. 0.05 mm: 788lC. The hydrochloride of this compound has mp. 15 l-l54C, and the hydrobromide has mp. 158C.

EXAMPLE 3 Resolution of racemic 3-methoxymethyl- 1 -methyl- 1 -4-phenylpiperidine a. To a solution of ()dibenzoyltartaric acid (7.l g) in 99% ethanol ml) was added (i)emethoxymethyl-l-methyl-4-phenylpiperidine (8.8 g). After evaporation of the solvent the evaporation residue was recrystallized from benzene (80 ml) to give 5 g of the dibenzoyltartrate, m.p. l52l54C. This was dissolved in a mixture of 4N sodium hydroxyde 10 ml) and ether (20 ml), and the ether layer was separated,

dried over potassium carbonate, and evaporated to dryness. The evaporation residue was treated with hydrobromic acid, the water removed in vacuo, and the residue recrystallized from ethanol and ether to yield the hydrobromide, mp. 178-180C. [a] =+36 (C 7% in 99% ethanol).

b. The benzene from the recrystallization mentioned under (a) above was evaporated, and the evaporation residue dissolved in a mixture of 4N sodium hydroxyde (20 ml) and ether (20 ml). The ether layer was separated, dried over potassium carbonate, and evaporated. The residue (4.6 g) was added to a solution of 1 (+)dibenzoyltartaric acid (3.7 g) in 99% ethano1.( ml), whereupon the procedure was as described under a). The hydrobromide has m.p. 179-180C, and [a] 37 (c 7% in 99% ethanol).

EXAMPLE 4 (a)-3-Methoxymethyl-1-methyl-4-pheny1piperidine (a)-3-hydroxymethyl-1-methyl-4-phenylpiperidine (6.15 g) was added to a suspension of sodium hydride (1.6 g), in oil) in dry dimethylformamide. The 1 was made alkaline with 4N sodium hydroxyde (10 ml) a yield 4 g of and extracted with ether. The ether extract was dried over potassium carbonate, the ether was removed by distillation, and the residue was distilled in vacuo to (a)-3-methoxymethyl-l-methyl-4- phenylpiperidine, b.p. 72-74C (0.05 mm).

With hydrobromic acid, the hydrobromide was prepared, m.p. 158-l60C.

EXAMPLE 5 (B )-3-Methoxymethyl l -methyl-4-phenylpiperidine hydrobromide The procedure described in Example 4 was followed except that the (B)-3-hydroxymethyl compound was used instead of the (a) compound.

The hydrobromide obtained had mp. 201-204C.

EXAMPLE 6 A mixture of 16.5 g of a-3-hydroxymethy1-l-methyl- 4-phenylpiperidine, 12.5 g of 4-methoxyphenol and 16.5 g of dicyclohexylcarbodiimide was heated to l180C for 24 hours. After cooling, 200 ml of ether were added to dissolve the product. The separated dicyclohexylurea was removed by tiltration, and the solution was extracted with 200 ml of 0.5N hydrochloric acid. From the acid solution, the hydrochloride of the a-compound was prepared in the usual way.

EXAMPLES 7-67 Using one or the other of the methods described in Examples 1-6, the compounds listed below were prepared;

a forms R Methyl Code R X M.p. Salt GF 01 Methyl H 151-154 HCI -166 l-lBr Y racemic form 179-180 HBr GF 02 Ethyl 169-171 HCl GF 03 Methyl Z-MethyI 189-190 HBr GF 04 Methyl 4-F1uor 123-130 HBr GF 05 Methyl 2-Methoxy 171-174 HBr GF 06 Methyl 3-Trit1uormethyl 92-94 maleate racemic form 129-131 HBr GF 07 Methyl 4-tert.butyl 143-145 maleate GP 08 Methyl 3-Methoxy 100-102 maleate GF, 09 Methyl 4-Chloro I 104-105 maleate GF 10 Z-Propyl 1-1 179-181 HC1 GF 11 Methyl 3-Hydroxy 222-223 HCI GF 12' Methyl 4-Methoxy. 1 103-104 maleate GF 13 Methyl 4-Hydroxy 230-233 HCl GF 14 t.-Buty1 H 195-197 HBr GF 15 Phenyl H 220-223 HBr I GF 16 4-Chlorophenyl H 199-202 HBr GF 17 4-Methoxyphenyl 1-1 234-235 HBr GF 18 Z-Methoxyphenyl 11 164-166 HBr GF 19 3-Methoxyphenyl H 176-179 HBr GF 20 4-Ethoxyphenyl H -187 HBr GF 21 3,5-Dimethoxypheny H 166-169 HBr GF 22 Methyl 4-Bromo 249-250 HBr GF 23 4-Methoxyphenyl 4-Methoxy 211-212 HCl 1 GF 24 Phenyl 4-fluoro 203-206 .HCl GF 25 Phenyl 4-Methoxy 213-215 HCl GF 26 4-Methoxyphenyl 4-Fluoro 227-230 HC1 GF 27 Phenyl 4-Chloro 201-203 HCI GF 28 4-Methoxyphenyl 4-Chloro 217-219 HCl GF 29 4-Methylsulfonylphenyl H 146-148 HCl GF 30 4-Methy1thiophenyl H 210-212 HCl GF 31 4-Methoxyp11eny1 H (-)form -192 HCl GF 32 4-Methoxyphenyl H (+)form 191-193 HCl GF 33 Phenyl 4-Methylthio 222-226 HCl GF 34 4-Methoxyphenyl 4-Methylthio 240-242 HCI As stated hereinbefore, the compounds of formula 1 are useful as antidepressants and as anti-Parkinson drugs as indicated by their biochemical and pharmacological properties.

At present the antidepressants most used in the clinic are the tricyclic thymoleptics (e.g. lmipramine and Amitriptyline). These drugs act by centrally potentiating serotonin (SHT) and noradrenaline (NA) as a consequence of neuronal reuptake inhibition.

The same potentiating action of the new compounds was confirmed by determinating SHT- and NA-uptake inhibition in virtro using synaptosomes prepared from different regions of rat brain. Some of the compounds,

e.g. GF 32, GF 52, and GF 57, are especially strong in- SHT-uptake inhibitory activity Antagonism of p-chloroamphetamine induced SHT-depletion from rat brain:

(PCA)- Contmued Q X CH,0R

a forms R Methyl Code R X M.p. Salt GF 4-Acetylaminophenyl H 243-247 HCl GF 36 4-Methoxyphenyl H 110-111 (CH,COOH GF 37 Z-Propynyl H 121-131 (=CHCOOH GF 38 1,3-benzdioxolyl-(5) H 244-246 HCl GF 39 2-t.-Buty1phenyl H 185-188 HCI GF 40 3,4-Dimethoxyphenyl H 230-233 HCl 61- 48 Phenyl H form 173-174 HBr GF 49 Phenyl H (+)form 173-174 HBr GF 50 4-Methoxypheny1 4-Hydroxy 113-115 HCI GF 51 1,3-Benzdioxolyl-(5) H (+)form 217 HCl GF 52 1,3-Benzdioxoly1-(5) H ()form 219 HCl GF 53 (1,2,3,4-Tetrahydronaphthyl-( 3)) H 214-217 HCl GF 54 4-Methoxyphenyl 4-Benzyloxy 201-204 HCI R Propynyl GF 41 Methyl H 190-191 HBr GF 42 4-Methoxyphenyl H 170-172 HCI GF 55 4-Methoxyphenyl H (+)form 141-142 HCI GF 56 4-Methoxypheny1 H ()form 142-143 HCI GF 57 1,3-Benzdioxo1yl-(5) 1 H ()form 181-182 HCI GF 58 1,3-Benzdioxo1yl-(5) H (+)form 182-183 HCl R CH,GF, GF 59 4-Methoxypheny1 H ()form 123-128 dec. HCl GF 60 4-Methoxyphenyl H (+)form 116-120 dec. HCI GF 61 4-Methoxyphenyl H racemic form 142-143 HBr GF 43 4-Nitropheny1 H 219-224 HBr GF 44 3-Methy1 4-Chloro 225-228 HBr GF 3-Methy1 H 201-203 HBr GF 46 4-Aeetylaminophenyl H 258-262 HCl GF 47 4-Methoxypheny1 g H 186 HCl 1) 2) 40 Substance ED mglkg s.c. ED, mg/kg po.

GF 32 1.5 20 GF 61 1.4 GF 52 2.8 3.2 GF 57 0.5 2.0 lmipramine 8.0 44 45 Chlorimipramine 1.0 42

Amitriptyline 12 Protriptyline 1 Test drugs were administered s.c. simultaneously with PCA. 2) Test drugs were administered 2 hours before PCA.

50 The method is described by Squires (Acta phamacol.

et toxicol. 1972, 3-1 suppl. 1, 35).

1n all experiments, GF 32 induced heart bundle branch block at a significantly higher dose level than did the tricyclic thymoleptics.

In dogs, the infusion produced an initial positive inotropic effect. GF 32 showed this property in the dose range l-25 mg/kg,1mipramine and Amitriptyline .at l-6 mg/kg. Higher doses produced negative inotropic effects, No ECG changes werefound in dogs during fourweeks of daily administration of GP 32 in doses of activity. Benztropine and some related anti-Parkinson drugs inhibit DA re-uptake, in addition to havingstrong anticholinergic effects, which may cause some of the most common adverse effects of these compounds. The

compounds of this invention are almost devoid of anticholinergic effect. N (1) Activity as dopamine-potentiators X Potentiation of apomorphine-induced gnawing in mice: 5 CHHOR wherein:

l 1 v R represents alkyl of 1-4 carbon atoms; alkynyl of Substance I ED mglkg 5., Maximal responsc 2-4 carbon atoms; phenyl; phenyl substituted by 0F i4, 7 I39 10 alkyl of one to four carbon atoms, alkoxy of one to GF 5 28 224 four carbon atoms, alkylthio of one to four carbon 7 v vC-F 48 43 I26 atoms, halogen, nitro, acetylamino, methylsulfonyl,

" gf f m g; or by methylenedioxo; or tetrahydronaphthyl;

j R represents hydrogen; alkyl of l4 carbon atoms;

' alkynyl of 2-4 carbon atoms; or 2,2,2-

- trifluoroethyl; The toxicity of the compounds of the invention is X represents hydrogen; alkyl or carbo" atoms; about the same as that of the tricyclic thymoleptics, but "ifluoromethyl; methoxy; halogen; hydroxy; meth some compounds, e.g. GF 32, are less toxic. Y or benzyloxy;

' I and a salt thereof with a pharmaceutically acceptable acid. 2. A compound according to claim 1, in which R is Acute toxicity in mice h nyl substance mg/kg "lg/kg 3. A compound according to claim 1, in which R is 'GF 53 941 I408 4-methoxyphenyl. 2g H gg S88 4. A compound according to claim 1, in which R is :G-F 49' 400 40 1,3-benzdioxolyl.

. y 7 l 28 :83 5. The compound according to claim 1, in which R vlmipmmine f 385 M2 is phenyl, R is methyl, and X is hydrogen.

Amilriplxline I26 280 30 6. The compound according to claim 1, in which R aemmpne 75 is 4-methoxyphenyl', R is methyl, and X is hydrogen. 7. The compound according to claim 1, in which R is 1,3-benzdioxolyl-5, and R and X are hydrogen. v 8. The compound according to claim 1, in which R y We claim:

is l,3-benzdioxolyl-5, R is methyl, and X is hydrogen.

1 A 3-substituted 4-phenylpiperidine of the formula 

1. A 3-SUBSTITUTED 4-PHENLPIPERIDINE OF THE FORMULA
 2. A compound according to claim 1, in which R is phenyl.
 3. A compound according to claim 1, in which R is 4-methoxyphenyl.
 4. A compound according to claim 1, in which R is 1,3-benzdioxolyl.
 5. The compound according to claim 1, in which R is phenyl, R1 is methyl, and X is hydrogen.
 6. The compound according to claim 1, in which R is 4-methoxyphenyl, R1 is methyl, and X is hydrogen.
 7. The compound according to claim 1, in which R is 1,3-benzdioxolyl-5, and R1 and X are hydrogen.
 8. The compound according to claim 1, in which R is 1,3-benzdioxolyl-5, R1 is methyl, and X is hydrogen. 